Maybe this will be helpful to others. Make sure you have enough uninterrupted time to take the quizzes. On two different occasions, due to interruptions from my children, as I was in the middle of a quiz, I lost my results. I think it was because it timed out. I don't remember hitting something that would have lost the quiz, but this is my first time doing something like this. So, I have had to forewarn my kids, "I am about to take a quiz, so please give me 30-minutes uninterrupted." While the quiz does not take long, if you get interrupted for an extended period of time, you might lose your responses. Again, maybe you have not had that issue, but if you have, that could be the reason why.
I hope this is helpful!
Rich G.